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Submitting Drivers For The Linux Kernel
---------------------------------------

This document is intended to explain how to submit device drivers to the
various kernel trees. Note that if you are interested in video card drivers
you should probably talk to XFree86 (http://www.xfree86.org) instead.

Also read the Documentation/SubmittingPatches document.


Allocating Device Numbers
-------------------------

Major and minor numbers for block and character devices are allocated
by the Linux assigned name and number authority (currently better
known as H Peter Anvin). The site is http://www.lanana.org/. This
also deals with allocating numbers for devices that are not going to
be submitted to the mainstream kernel.

If you don't use assigned numbers then when you device is submitted it will
get given an assigned number even if that is different from values you may
have shipped to customers before.

Who To Submit Drivers To
------------------------

Linux 2.0:
        No new drivers are accepted for this kernel tree

Linux 2.2:
        If the code area has a general maintainer then please submit it to
        the maintainer listed in MAINTAINERS in the kernel file. If the
        maintainer does not respond or you cannot find the appropriate
        maintainer then please contact Alan Cox <alan@lxorguk.ukuu.org.uk>

Linux 2.4:
        The same rules apply as 2.2. The final contact point for Linux 2.4 
        submissions is Marcelo Tosatti <marcelo.tosatti@cyclades.com>.

Linux 2.5:
        The same rules apply as 2.4 except that you should follow linux-kernel
        to track changes in API's. The final contact point for Linux 2.5
        submissions is Linus Torvalds <torvalds@osdl.org>.

What Criteria Determine Acceptance
----------------------------------

Licensing:      The code must be released to us under the
                GNU General Public License. We don't insist on any kind
                of exclusively GPL licensing, and if you wish the driver
                to be useful to other communities such as BSD you may well
                wish to release under multiple licenses.

Interfaces:     If your driver uses existing interfaces and behaves like
                other drivers in the same class it will be much more likely
                to be accepted than if it invents gratuitous new ones. 
                If you need to implement a common API over Linux and NT
                drivers do it in userspace.

Code:           Please use the Linux style of code formatting as documented
                in Documentation/CodingStyle. If you have sections of code
                that need to be in other formats, for example because they
                are shared with a windows driver kit and you want to
                maintain them just once seperate them out nicely and note
                this fact.

Portability:    Pointers are not always 32bits, not all computers are little
                endian, people do not all have floating point and you
                shouldn't use inline x86 assembler in your driver without
                careful thought. Pure x86 drivers generally are not popular.
                If you only have x86 hardware it is hard to test portability
                but it is easy to make sure the code can easily be made
                portable.

Clarity:        It helps if anyone can see how to fix the driver. It helps
                you because you get patches not bug reports. If you submit a
                driver that intentionally obfuscates how the hardware works
                it will go in the bitbucket.

Control:        In general if there is active maintainance of a driver by
                the author then patches will be redirected to them unless 
                they are totally obvious and without need of checking.
                If you want to be the contact and update point for the
                driver it is a good idea to state this in the comments,
                and include an entry in MAINTAINERS for your driver.

What Criteria Do Not Determine Acceptance
-----------------------------------------

Vendor:         Being the hardware vendor and maintaining the driver is
                often a good thing. If there is a stable working driver from
                other people already in the tree don't expect 'we are the
                vendor' to get your driver chosen. Ideally work with the 
                existing driver author to build a single perfect driver.

Author:         It doesn't matter if a large Linux company wrote the driver,
                or you did. Nobody has any special access to the kernel
                tree. Anyone who tells you otherwise isn't telling the
                whole story.


Resources
---------

Linux kernel master tree:
        ftp.??.kernel.org:/pub/linux/kernel/...
        ?? == your country code, such as "us", "uk", "fr", etc.

Linux kernel mailing list:              
        linux-kernel@vger.kernel.org
        [mail majordomo@vger.kernel.org to subscribe]

Kernel traffic:
        Weekly summary of kernel list activity (much easier to read)
        [http://kt.zork.net/kernel-traffic]

Linux USB project:
        http://sourceforge.net/projects/linux-usb/